The evolutionary history of phytophagous insects and mites and of their food-plants is traced in the conservative preferences of modern-day insects for plants. Based on UK data in the Phytophagous Insects Data Bank, a correspondence analysis displays 182 insect families and 117 plant families in a bi-variate plot. The overall pattern suggests the expansion of diversity of insects and host plants from Gymnosperms to Dicots. Plots for phytophagous insect orders and major plant clades are described, with families provisionally ranked as evolutionarily basal, intermediate or advanced. There are blurred patterns of evolutionary advancement from basal insect families with more species on conifers and on ferns and Eurosid I trees. Intermediate families are commoner on Malpighiales and Fabales, and advanced insects more frequent on later evolved euasterids II (Asterales and Lamiales), Caryophyllales and Gramineae. Basal Hymenoptera have associations with conifers, basal Lepidoptera to Eurosid I trees, and Diptera are mainly advanced families on commelinids (grasses) and Asteraceae. Blurred traces of similar phylogenetic sequences are described for subfamilies within eight example insect families. Basal families and clades tend to have fewer species than derived advanced clades. Insect communities on plants should be seen in the light of this linked past evolutionary background. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78, 51–83.